Biosensors

12 pages, 2021 KiB

Open AccessArticle

Probing the Influence of Specular Reflection and Overexposure on Backscattering Mueller Matrix Polarimetry for Tissue Imaging and Sensing

by Wei Jiao, Nan Zeng, Rui Hao, Hui Ma, Chao He and Honghui He

Biosensors 2025, 15(5), 333; https://doi.org/10.3390/bios15050333 - 21 May 2025

Viewed by 332

Abstract

Mueller matrix polarimetry has great potential for tissue detection and clinical diagnosis due to its ability to provide rich microstructural information accurately. However, in practical in vivo tissue imaging based on backscattering Mueller matrix polarimetry, specular reflection is often inevitable, leading to overexposed [...] Read more.

Mueller matrix polarimetry has great potential for tissue detection and clinical diagnosis due to its ability to provide rich microstructural information accurately. However, in practical in vivo tissue imaging based on backscattering Mueller matrix polarimetry, specular reflection is often inevitable, leading to overexposed regions and the following inaccurate polarization information acquisition of tissues. In this study, we probe the influence of specular reflection and overexposure on backscattering Mueller matrix polarimetry for tissue imaging and sensing. We investigate in detail the differentiation of polarization behaviors between the specular reflection and non-specular reflection tissue regions using a 3 × 3 backscattering Mueller matrix measurement. Then, we obtain the vertical projection profiles to further quantify the Mueller matrix elements of porcine liver tissue in different specular reflection regions. Finally, we calculate the polarization feature parameters derived from a 3 × 3 Mueller matrix and analyze their behavior in overexposed regions. Based on the quantitative analysis and comparisons, we obtain a group of polarization feature parameters with strong immunity to the specular reflection process. This study offers a strategy for selecting the polarization parameters during in vivo polarimetric imaging applications, provides valuable references for further eliminating the characterization errors induced by specular reflection, and may contribute to the advancement of quantitative tissue polarimetric imaging and sensing. Full article

(This article belongs to the Special Issue Photonics for Bioapplications: Sensors and Technology—2nd Edition)

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15 pages, 2677 KiB

Open AccessArticle

Enzyme-Based Solid-Phase Electrochemiluminescence Sensors with Stable, Anchored Emitters for Sensitive Glucose Detection

by Chunyin Wei, Yanyan Zheng, Fei Yan and Lifang Xu

Biosensors 2025, 15(5), 332; https://doi.org/10.3390/bios15050332 - 21 May 2025

Viewed by 275

Abstract

Glucose (Glu) detection, as a fundamental analytical technique, has applications in medical diagnostics, clinical testing, bioanalysis and environmental monitoring. In this work, a solid-phase electrochemiluminescence (ECL) enzyme sensor was developed by immobilizing the ECL emitter in a stable manner within bipolar silica nanochannel [...] Read more.

Glucose (Glu) detection, as a fundamental analytical technique, has applications in medical diagnostics, clinical testing, bioanalysis and environmental monitoring. In this work, a solid-phase electrochemiluminescence (ECL) enzyme sensor was developed by immobilizing the ECL emitter in a stable manner within bipolar silica nanochannel array film (bp-SNA), enabling sensitive glucose detection. The sensor was constructed using an electrochemical-assisted self-assembly (EASA) method with various siloxane precursors to quickly modify the surface of indium tin oxide (ITO) electrodes with a bilayer SNA of different charge properties. The inner layer, including negatively charged SNA (n-SNA), attracted the positively charged ECL emitter tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) via electrostatic interaction, while the outer layer, including positively charged SNA (p-SNA), repelled it, forming a barrier that efficiently concentrated the Ru(bpy)₃²⁺ emitter in a stable manner. After modifying the amine groups on the p-SNA surface with aldehyde groups, glucose oxidase (GOx) was covalently immobilized, forming the enzyme electrode. In the presence of glucose, GOx catalyzed the conversion of glucose to hydrogen peroxide (H₂O₂), which acted as a quencher for the Ru(bpy)₃²⁺/triethanolamine (TPA) system, reducing the ECL signal and enabling quantitative glucose analysis. The sensor exhibited a wide linear range from 10 μM to 7.0 mM and a limit of detection (LOD) of 1 μM (S/N = 3). Glucose detection in fetal bovine serum was realized. By replacing the enzyme type on the electrode surface, this sensing strategy holds the potential to provide a universal platform for the detection of different metabolites. Full article

(This article belongs to the Special Issue Recent Developments in Nanomaterial-Based Electrochemical Biosensors)

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15 pages, 902 KiB

Open AccessArticle

Silver Nanoparticles for Biosensing and Drug Delivery: A Mechanical Study on DNA Interaction

by Katarína Nemčeková, Patrícia Dudoňová, Tomáš Holka, Sabína Balážová, Michaela Hornychová, Viktória Szebellaiová, Monika Naumowicz, Pavol Gemeiner, Tomáš Mackuľak, Miroslav Gál and Veronika Svitková

Biosensors 2025, 15(5), 331; https://doi.org/10.3390/bios15050331 - 21 May 2025

Viewed by 352

Abstract

Silver nanoparticles (AgNPs) have attracted tremendous attention in recent years due to their unique physicochemical properties, including pronounced surface plasmon resonance, tunable size, and amenability to functionalization. These attributes underpin the growing interest in AgNPs as SMART nanocarriers for targeted drug delivery and [...] Read more.

Silver nanoparticles (AgNPs) have attracted tremendous attention in recent years due to their unique physicochemical properties, including pronounced surface plasmon resonance, tunable size, and amenability to functionalization. These attributes underpin the growing interest in AgNPs as SMART nanocarriers for targeted drug delivery and as active components in biosensing platforms. In this work, we discuss various synthesis strategies for AgNPs—ranging from conventional chemical methods to green approaches—and highlight their subsequent functionalization with anticancer drugs, notably doxorubicin (DOX). We also examine the potential of AgNPs in biosensor applications, emphasizing electrochemical and optical detection modalities capable of monitoring drug release, oxidative stress, and relevant biomarkers. Our experimental data support the conclusion that AgNPs can effectively improve therapeutic efficacy by exploiting tumor-specific conditions (e.g., lower pH) while also enhancing biosensor sensitivity via surface plasmon resonance and electrochemical signal amplification. We provide a thorough discussion of the results, including mechanistic aspects of reactive oxygen species (ROS) generation, drug release kinetics, and sensor performance metrics. Overall, AgNP-based nanocarriers emerge as a powerful platform to address current challenges in precision oncology and medical diagnostics. Full article

(This article belongs to the Special Issue Nanotechnology-Based Biosensors in Drug Delivery)

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15 pages, 2152 KiB

Open AccessArticle

Ultrasensitive Analysis of BRCA-1 Based on Gold Nanoparticles and Molybdenum Disulfide Electrochemical Immunosensor with Enhanced Signal Amplification

by Derya Bal Altuntaş

Biosensors 2025, 15(5), 330; https://doi.org/10.3390/bios15050330 - 21 May 2025

Viewed by 248

Abstract

The BRCA-1 protein, recognized for its diagnostic relevance in a wide spectrum of malignancies, has been the focus of extensive investigation. In this study, an electrochemical immunosensor specifically designed for BRCA-1 detection was fabricated. The sensing platform utilizes disposable pencil graphite electrodes modified [...] Read more.

The BRCA-1 protein, recognized for its diagnostic relevance in a wide spectrum of malignancies, has been the focus of extensive investigation. In this study, an electrochemical immunosensor specifically designed for BRCA-1 detection was fabricated. The sensing platform utilizes disposable pencil graphite electrodes modified with a nanocomposite composed of gold nanoparticles (AuNPs), molybdenum disulfide (MoS₂), and chitosan (CS). This multifunctional nanostructure significantly promotes electron transfer efficiency and supports the effective immobilization of antibodies. The constructed immunosensor exhibited excellent analytical performance, with a linear detection range between 0.05 and 20 ng/mL for BRCA-1 and a notably low limit of detection at 0.04 ng/mL. The device maintained a relative standard deviation of 3.59% (n = 3), indicating strong reproducibility. In addition, a high recovery rate of 98 ± 3% was achieved in spiked serum samples, even in the presence of common electroactive interferents such as dopamine and ascorbic acid. These findings highlight the sensor’s promising applicability for the clinical detection of BRCA-1 and potentially other cancer-related biomarkers. Full article

(This article belongs to the Section Biosensor Materials)

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13 pages, 1462 KiB

Open AccessArticle

Molecularly Imprinted SERS Plasmonic Sensor for the Detection of Malachite Green

by Hao Zhang, Dani Sun, Yuhao Wen, Mengyuan Wang, Jingying Huang, Ziru Lian and Jinhua Li

Biosensors 2025, 15(5), 329; https://doi.org/10.3390/bios15050329 - 20 May 2025

Viewed by 281

Abstract

Malachite green (MG) is a highly toxic dye commonly used in industries and aquaculture, leading to significant environmental contamination and health hazards. Therefore, sensitive and selective detection of MG in real samples is urgently needed. This study presents the development of a molecularly [...] Read more.

Malachite green (MG) is a highly toxic dye commonly used in industries and aquaculture, leading to significant environmental contamination and health hazards. Therefore, sensitive and selective detection of MG in real samples is urgently needed. This study presents the development of a molecularly imprinted surface-enhanced Raman spectroscopy (MI-SERS) plasmonic sensor for the rapid and sensitive detection of MG. The sensor consists of a gold nanostar (Au NS) layer as the SERS substrate and an imprinted polydopamine layer containing specific recognition sites for MG. Taking full advantage of the plasmonic effect of SERS and selective recognition capability of imprinted materials, under optimized conditions, the sensor demonstrated high sensitivity, with a detection limit of 3.5 × 10⁻³ mg/L, excellent selectivity against interference from other organic dyes, and robust performance with recoveries of 90.2–114.2% in real seawater samples. The MI-SERS sensor also exhibited good reproducibility, stability, and reusability. These findings suggest that the MI-SERS sensor is a promising tool for real-time monitoring of MG contamination in complicated samples. Full article

(This article belongs to the Special Issue Miniature Sensors Based on Highly Efficient Chemical and Biological Sensing Interfaces)

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38 pages, 7289 KiB

Open AccessReview

The Biomodification and Biomimetic Synthesis of 2D Nanomaterial-Based Nanohybrids for Biosensor Applications: A Review

by Ranran Wang, Xinyue Wang, Yan Wang and Gang Wei

Biosensors 2025, 15(5), 328; https://doi.org/10.3390/bios15050328 - 20 May 2025

Viewed by 351

Abstract

Two-dimensional nanomaterials (2DNMs) exhibit significant potential for the development of functional and specifically targeted biosensors, owing to their unique planar nanosheet structures and distinct physical and chemical properties. Biomodification and biomimetic synthesis offer green and mild approaches for the fabrication of multifunctional nanohybrids [...] Read more.

Two-dimensional nanomaterials (2DNMs) exhibit significant potential for the development of functional and specifically targeted biosensors, owing to their unique planar nanosheet structures and distinct physical and chemical properties. Biomodification and biomimetic synthesis offer green and mild approaches for the fabrication of multifunctional nanohybrids with enhanced catalytic, fluorescent, electronic, and optical properties, thereby expanding their utility in constructing high-performance biosensors. In this review, we present recent advances in the synthesis of 2DNM-based nanohybrids via both biomodification and biomimetic strategies for biosensor applications. We discuss covalent and non-covalent biomodification methods involving various biomolecules, including peptides, proteins, DNA/RNA, enzymes, biopolymers, and bioactive polysaccharides. The engineering of biomolecule–nanomaterial interfaces for the creation of biomodified 2DNM-based nanohybrids is also explored. Furthermore, we summarize the biomimetic synthesis of 2DNM-based bio–nanohybrids through pathways such as bio-templating, biomolecule-directed self-assembly, biomineralization, and biomimetic functional integration. The potential applications of these nanohybrids in diverse biosensing platforms—including colorimetric, surface plasmon resonance, electrochemical, fluorescence, photoelectrochemical, and integrated multimodal biosensors—are introduced and discussed. Finally, we analyze the opportunities and challenges associated with this rapidly developing field. We believe this comprehensive review will provide valuable insights into the biofunctionalization of 2DNMs and guide the rational design of advanced biosensors for diagnostic applications. Full article

(This article belongs to the Special Issue Nano- and Micro-biosensing Technologies)

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20 pages, 5093 KiB

Open AccessReview

Convenient Biochemical Testing Technologies for Oral Disease Risk Warning: Opportunities and Challenges

by Ying Liu, Jincheng Xu, Siyuan Wang, Yuanfang Li, Li Ji, Dong Xie and Jianhua Zhou

Biosensors 2025, 15(5), 327; https://doi.org/10.3390/bios15050327 - 20 May 2025

Viewed by 341

Abstract

In recent years, attention toward oral health issues has increased with economic development and improvements in quality of life. Biochemical testing technologies offer an efficient method for identifying insidious pathological changes in the oral cavity. Frequent home-based self-screening can enable early identification of [...] Read more.

In recent years, attention toward oral health issues has increased with economic development and improvements in quality of life. Biochemical testing technologies offer an efficient method for identifying insidious pathological changes in the oral cavity. Frequent home-based self-screening can enable early identification of dental disease risks, thus facilitating timely interventions. Convenient home-based biochemical testing methods must be user-friendly, cost-effective, and operable without specialized equipment or extensive training. This review summarizes recent advances in convenient biochemical testing methods for the detection and diagnosis of oral diseases, focusing on their reliability, user compliance, and practicality for home-based applications. This review highlights the significance of biomarker distribution imaging for simultaneously identifying multiple lesions and provides perspectives on future research directions. By promoting interdisciplinary collaboration in biochemical diagnostics, this review outlines pathways toward personalized oral healthcare, precision dentistry, and enhanced overall health outcomes. Full article

(This article belongs to the Special Issue Biosensing and Diagnosis—2nd Edition)

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16 pages, 3297 KiB

Open AccessArticle

On the Possibility of Fluorescent Capture Immunoassays on a Contact Lens

by Kundan Sivashanmugan, E. Albert Reece and Joseph R. Lakowicz

Biosensors 2025, 15(5), 326; https://doi.org/10.3390/bios15050326 - 20 May 2025

Viewed by 253

Abstract

Blood samples and testing are routine in healthcare. Presently, there is a growing interest in using tear samples in place of blood. Tear samples can be obtained non-invasively and collection does not require the skills of a trained phlebotomist. Red blood cells and [...] Read more.

Blood samples and testing are routine in healthcare. Presently, there is a growing interest in using tear samples in place of blood. Tear samples can be obtained non-invasively and collection does not require the skills of a trained phlebotomist. Red blood cells and other cells are not present in tears, which avoids centrifugation. Importantly, basal tear samples contain most of the biomarkers present in blood. The difficulty is the small volume of basal tears, which is about 7 μL in each eye. Any contact with the eye results in additional reflex tears with a different chemical composition. The small tear samples are collected with capillary tubes and then sent out for amplified assays, such as enzyme-linked immunosorbent assay (ELISA) or polymerase chain reaction (PCR). The results are not available for several days or a week and, therefore, are less useful in an ophthalmology office. We propose the use of a contact lens that contains bound antibodies for fluorescence immunoassays. The lenses could be removed from the patient for point-of-care measurements at the bedside. To prove that this concept is possible, we performed a three-layer protein capture assay that mimics an immunoassay. For convenience, we used lysozyme (Lys), which spontaneously coats silicon hydrogel (SiHG) contact lenses (CL). Anti-lysozyme IgG was the second layer captured, with anti-lysozyme considered to be the target biomarker. The third layer was rhodamine or Alexa Fluor-labeled Ab against the IgG Fc region, considered to be the detection antibody. The multiple protein layers were stable and did not wash off the SiHG lenses. These results strongly suggest the contact lens can be used for capture immunoassays for a wide variety of biomarkers. Full article

(This article belongs to the Topic Applications of Nanomaterials in Biosensing: Current Trends and Future Prospects)

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Graphical abstract

18 pages, 6821 KiB

Open AccessArticle

Strain Plethysmography Using a Hermetically Sealed MEMS Strain Sensor

by Xinyu Jiang, Brian Sang, Haoran Wen, Gregory Junek, Jin-Woo Park and Farrokh Ayazi

Biosensors 2025, 15(5), 325; https://doi.org/10.3390/bios15050325 - 20 May 2025

Viewed by 338

Abstract

We present a hermetically sealed capacitive microelectromechanical system (MEMS) strain sensor designed for arterial pulse waveform extraction using the strain plethysmography (SPG) modality. The MEMS strain sensor features a small form factor of 3.3 mm × 3.3 mm × 1 mm, leverages a [...] Read more.

We present a hermetically sealed capacitive microelectromechanical system (MEMS) strain sensor designed for arterial pulse waveform extraction using the strain plethysmography (SPG) modality. The MEMS strain sensor features a small form factor of 3.3 mm × 3.3 mm × 1 mm, leverages a nano-gap fabrication process to improve the sensitivity, and uses a differential sensing mechanism to improve the linearity and remove the common mode drift. The MEMS strain sensor is interfaced with an application-specific integrated circuit (ASIC) to form a compact strain sensing system. This system exhibits a high strain sensitivity of 316 aF/µε, a gauge factor (GF) of 35, and a strain sensing resolution of 1.26 µε, while maintaining a linear range exceeding 700 µε. SPG signals have been reliably captured at both the fingertip and wrist using the MEMS strain sensor with high signal quality, preserving various photoplethysmography (PPG) features. Experimental results demonstrate that heart rate (HR) and heart rate variability (HRV) can be estimated from the SPG signal collected at the fingertip and wrist using the sensor with an accuracy of over 99%. Pulse arrival time (PAT) and pulse transit time (PTT) have been successfully extracted using the sensor together with a MEMS seismometer, showcasing its potential for ambulatory BP monitoring (ABPM) application. Full article

(This article belongs to the Special Issue Biosensors for Monitoring and Diagnostics)

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44 pages, 16366 KiB

Open AccessReview

Recent Advances in Paper-Based Electronics: Emphasis on Field-Effect Transistors and Sensors

by Dimitris Barmpakos, Apostolos Apostolakis, Fadi Jaber, Konstantinos Aidinis and Grigoris Kaltsas

Biosensors 2025, 15(5), 324; https://doi.org/10.3390/bios15050324 - 19 May 2025

Viewed by 608

Abstract

Paper-based electronics have emerged as a sustainable, low-cost, and flexible alternative to traditional substrates for electronics, particularly for disposable and wearable applications. This review outlines recent developments in paper-based devices, focusing on sensors and paper-based field-effect transistors (PFETs). Key fabrication techniques such as [...] Read more.

Paper-based electronics have emerged as a sustainable, low-cost, and flexible alternative to traditional substrates for electronics, particularly for disposable and wearable applications. This review outlines recent developments in paper-based devices, focusing on sensors and paper-based field-effect transistors (PFETs). Key fabrication techniques such as laser-induced graphene, inkjet printing, and screen printing have enabled the creation of highly sensitive and selective devices on various paper substrates. Material innovations, especially the integration of graphene, carbon-based materials, conductive polymers, and other novel micro- and nano-enabled materials, have significantly enhanced device performance. This review discusses modern applications of paper-based electronics, with a particular emphasis on biosensors, electrochemical and physical sensors, and PFETs designed for flexibility, low power, and high sensitivity. Advances in PFET architectures have further enabled the development of logic gates and memory systems on paper, highlighting the potential for fully integrated circuits. Despite challenges in durability and performance consistency, the field is rapidly evolving, driven by the demand for green electronics and the need for decentralized, point-of-care diagnostic tools. This paper also identifies detection strategies used in paper-based sensors, reviews limitations in the current fabrication methods, and outlines opportunities for the scalable production of multifunctional paper-based systems. This review addresses a critical gap in the literature by linking device-level innovation with real-world sensor applications on paper substrates. Full article

(This article belongs to the Special Issue Biosensing and Diagnosis—2nd Edition)

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15 pages, 835 KiB

Open AccessArticle

A Nanoparticle-Based Immunoassay on Facemasks for Evaluating Neutrophilic Airway Inflammation in COPD Patients

by Bartomeu Mestre, Nuria Toledo-Pons, Andreu Vaquer, Sofia Tejada, Antonio Clemente, Amanda Iglesias, Meritxell López, Ruth Engonga, Sabina Perelló, Borja G. Cosío and Roberto de la Rica

Biosensors 2025, 15(5), 323; https://doi.org/10.3390/bios15050323 - 19 May 2025

Viewed by 305

Abstract

Patients with chronic obstructive pulmonary disease (COPD) often experience acute exacerbations characterized by elevated neutrophilic inflammation in the lungs. Currently, this condition is diagnosed through visual inspection of sputum color and volume, a method prone to personal bias and unsuitable for patients who [...] Read more.

Patients with chronic obstructive pulmonary disease (COPD) often experience acute exacerbations characterized by elevated neutrophilic inflammation in the lungs. Currently, this condition is diagnosed through visual inspection of sputum color and volume, a method prone to personal bias and unsuitable for patients who are unable to expectorate spontaneously. In this manuscript, we present a novel approach for measuring and monitoring exhaled myeloperoxidase (MPO), a biomarker of neutrophilic airway inflammation, without the need for sputum analysis. The method involves analyzing an unmodified surgical facemask worn by the patient for 30 min using biosensing decals that transfer antibody-coated nanoparticles. These colloids specifically interact with MPO trapped by the facemask in a dose-dependent manner, enabling the quantification of MPO levels, with a dynamic range up to 3 · 10¹ µg·mL⁻¹. The proposed diagnostic approach successfully differentiated patients with acute exacerbations from stable patients with 100% sensitivity and specificity. Healthy individuals also showed significantly lower MPO levels compared to COPD patients. Our results suggest that facemask analysis could be a non-invasive diagnostic tool for airway diseases, particularly in patients unable to expectorate. Full article

(This article belongs to the Special Issue Advances in Portable and Wearable Sensing Systems for Biochemical Monitoring)

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12 pages, 4673 KiB

Open AccessArticle

Ultrasensitive and Real-Time Detection of Kanamycin Residues in Milk Using an Aptasensor Based on Microfluidic Capacitive Strategy

by Weidong Zheng, Jun Chai, Jayne Wu, Jian Zhang and Haochen Qi

Biosensors 2025, 15(5), 322; https://doi.org/10.3390/bios15050322 - 18 May 2025

Viewed by 339

Abstract

Kanamycin (KanR) is a widely used antibiotic in human and veterinary medicine, as well as in food production and livestock breeding. However, its environmental residue and bioaccumulation in the food chain pose a great threat to human health. A real-time and sensitive aptasensor [...] Read more.

Kanamycin (KanR) is a widely used antibiotic in human and veterinary medicine, as well as in food production and livestock breeding. However, its environmental residue and bioaccumulation in the food chain pose a great threat to human health. A real-time and sensitive aptasensor is developed for KanR detection based on a gold interdigitated electrode (IDE). A microfluidic alternating current electrothermal (ACET) effect is employed for rapid directional manipulation and enrichment of KanR molecules. As an ultrasensitive indicator, solid–liquid capacitance is adopted to reflect the tiny change on the IDE surface caused by target adsorption. The overall detection takes only 60 s from sample to result, and a wide linear detection range of 0.1 fM~1 pM, an ultra-low detection limit of 16.56 aM, and a high selectivity of 7752:1 are simultaneously achieved, with 5 times of repeated use and the shelf life of 10 days. Furthermore, the aptasensor shows excellent practicability in milk samples, with the spiked recovery rate ranging from 86.90% to 116.17%. This aptasensor with the detecting strategy provides a rapid, convenient, and cost-effective solution for real-time monitoring of KanR. Full article

(This article belongs to the Special Issue In Honor of Prof. Evgeny Katz: Biosensors: Science and Technology)

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15 pages, 4484 KiB

Open AccessArticle

A Highly Sensitive Electrochemical Immunosensor for Cortisol Detection

by Pritu Parna Sarkar, Ali Ashraf, Ahmed Hasnain Jalal, Fahmida Alam and Nazmul Islam

Biosensors 2025, 15(5), 321; https://doi.org/10.3390/bios15050321 - 17 May 2025

Viewed by 481

Abstract

In this research, an interdigitated gear-shaped working electrode is presented for cortisol sensing. Overall, the sensor was designed in a three-electrode system and was fabricated using direct laser scribing. A synthesized conductive ink based on graphene and polyaniline was further employed to enhance [...] Read more.

In this research, an interdigitated gear-shaped working electrode is presented for cortisol sensing. Overall, the sensor was designed in a three-electrode system and was fabricated using direct laser scribing. A synthesized conductive ink based on graphene and polyaniline was further employed to enhance the electrochemical performance of the sensor. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were employed for physicochemical characterization of the laser-induced graphene (LIG) sensor. Cortisol, a biomarker essential in detecting stress, was detected both in phosphate-buffered saline (PBS, pH = 7.4) and human serum within a linear range of 100 ng/mL to 100 µg/mL. Ferri/ferrocyanide was employed as the redox probe to detect cortisol in PBS. The electrochemical performance of the developed sensor was assessed via differential pulse voltammetry (DPV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. The electrochemical performance demonstrates high sensitivity and selectivity alongside strong repeatability (relative standard deviation (RSD) = 3.8%, n = 4) and reproducibility (RSD = 5.85%, n = 5). Overall, these results highlight the sensor’s reliability, high sensitivity, and repeatability and reproducibility in the detection of cortisol. The sensor successfully detected cortisol in the complex medium of human serum and effectively distinguished it in a ternary mixture containing cortisol and dopamine. Also, the use of direct laser writing on Kapton film makes the approach cost-effective and thus disposable, making it suitable for chronic stress diagnostics and neurological research applications. Full article

(This article belongs to the Special Issue Innovative Biosensing Technologies for Sustainable Healthcare)

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17 pages, 3092 KiB

Open AccessArticle

MIP-Modified Porous Silicon Optical Sensor for Interleukin-6 Label-Free Quantification

by Valeria Nocerino, Giulia Siciliano, Monica Bianco, Ilaria Rea, Principia Dardano, Maria Serena Chiriacò, Francesco Ferrara, Giuseppe Gigli, Elisabetta Primiceri and Luca De Stefano

Biosensors 2025, 15(5), 320; https://doi.org/10.3390/bios15050320 - 17 May 2025

Viewed by 303

Abstract

In this study, we present an innovative optical biosensor designed to detect Interleukin-6 (IL-6), a pivotal cytokine implicated in many pathological conditions. Our sensing platform is made of a porous silicon (PSi) nanostructured substrate modified with a thin (~5 nm) molecularly imprinted polymer [...] Read more.

In this study, we present an innovative optical biosensor designed to detect Interleukin-6 (IL-6), a pivotal cytokine implicated in many pathological conditions. Our sensing platform is made of a porous silicon (PSi) nanostructured substrate modified with a thin (~5 nm) molecularly imprinted polymer (MIP), ensuring both high specificity and sensitivity toward IL-6 molecules. The fabrication process involves electrochemical etching of silicon chips to create the porous structure, followed by the electrodeposition of the MIP, which is tailored to selectively bind the IL-6 target. Extensive testing over a broad IL-6 concentration range demonstrates a clear, proportional optical response, yielding a limit of detection (LOD) of 13 nM. Moreover, the biosensor robustness was verified by evaluating its performance in bovine serum, a complex biological matrix. Despite the presence of various interfering components, the sensor maintained its selectivity and displayed minimal matrix effects, underlining its practical applicability in real-world diagnostic scenarios. Full article

(This article belongs to the Section Biosensor and Bioelectronic Devices)

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11 pages, 7658 KiB

Open AccessArticle

Colorimetric Detection of microRNA-378 Based on Y-Shaped Structure Formed by Gold Nanoparticles and Catalytic Hairpin Self-Assembly

by Yahui Gao, Jinru Pan, Bingyuan Fan, Shan Wang, Qian Wang, Wanru Liu, Fang Hu and Wei Meng

Biosensors 2025, 15(5), 319; https://doi.org/10.3390/bios15050319 - 15 May 2025

Viewed by 319

Abstract

The timely and accurate detection of cancer is crucial for preventing disease progression and for the early treatment of confirmed cases. MiRNAs are cancer markers. In this study, a simple miRNA detection method is proposed. Three hairpins were designed based on gold nanoparticles [...] Read more.

The timely and accurate detection of cancer is crucial for preventing disease progression and for the early treatment of confirmed cases. MiRNAs are cancer markers. In this study, a simple miRNA detection method is proposed. Three hairpins were designed based on gold nanoparticles combined with catalytic hairpin assembly nucleic acid amplification technology. The low-pH method was used for rapid coupling, and hairpin H1 was opened by miR-378, triggering the cycle reaction and signal amplification and finally forming a Y-shaped structure, thereby narrowing the distance between gold nanoparticles and achieving colorimetric detection. The absorbance change (A₆₂₀/A₅₂₀) was proportional to the concentration of miR-378 (0.05–5 nM), with a detection limit of 0.05 nM. This method also has an evident detection effect on real samples. HeLa and L-02 cell extracts were analyzed using this method. The former showed no obvious color change, whereas the maximum absorption peak of the latter showed a red shift, and the color changed from red to purple. The minimum number of cells that could be detected using HeLa cells was 500 cells/mL. Full article

(This article belongs to the Special Issue Nano Biosensors and Their Applications for In Vivo/Vitro Diagnosis—2nd Edition)

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12 pages, 2162 KiB

Open AccessArticle

Development of Immunoassays for Foodborne Pathogenic Bacteria Detection Using PolyHRP for Signal Enhancement

by Yijia Zhang, Junkang Pan, Qiyi He, Zhihao Xu, Bruce D. Hammock and Dongyang Li

Biosensors 2025, 15(5), 318; https://doi.org/10.3390/bios15050318 - 15 May 2025

Viewed by 322

Abstract

The rapid and accurate detection of foodborne pathogens is essential for ensuring food safety. Escherichia coli O157:H7 (E. coli O157:H7) and Salmonella Typhimurium (S. Typhimurium) are major foodborne pathogenic bacteria that pose significant public health risks, highlighting the need for [...] Read more.

The rapid and accurate detection of foodborne pathogens is essential for ensuring food safety. Escherichia coli O157:H7 (E. coli O157:H7) and Salmonella Typhimurium (S. Typhimurium) are major foodborne pathogenic bacteria that pose significant public health risks, highlighting the need for effective detection methods. In this study, highly sensitive double-antibody sandwich-based enzyme-linked immunosorbent assays (ELISAs) were developed for the rapid detection of E. coli O157:H7 and S. Typhimurium, utilizing a streptavidin-polymerized horseradish peroxidase (SA-PolyHRP)-based signal enhancement system. Systematic optimization was performed on key parameters, including the capture antibody concentration, detection antibody, and blocking agent. Compared to the method using SA-HRP, substitution with SA-PolyHRP significantly improved detection sensitivity, achieving limits of detection (LODs) of 1.4 × 10⁴ CFU/mL for E. coli O157:H7 and 6.0 × 10³ CFU/mL for S. Typhimurium, with sensitivity enhancements of 7.86-fold and 1.83-fold, respectively. Specificity tests confirmed no cross-reactivity with non-target or closely related pathogenic strains. The matrix effect was effectively mitigated through 10-fold and 100-fold dilutions for E. coli O157:H7 and S. Typhimurium, respectively. Both pathogens were successfully detected in beef samples spiked with 5 CFU after 5 h of incubation. This study demonstrates the effectiveness of PolyHRP-based signal enhancement for the highly sensitive and specific detection of foodborne pathogens, offering a promising approach for rapid food safety monitoring and public health protection. Full article

(This article belongs to the Special Issue Biosensors for Environmental Monitoring and Food Safety)

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11 pages, 2145 KiB

Open AccessArticle

One-Pot Detection of miRNA by Dual Rolling Circle Amplification at Ambient Temperature with High Specificity and Sensitivity

by Wenhua Sun, Kunling Hu, Ziting Song, Ran An and Xingguo Liang

Biosensors 2025, 15(5), 317; https://doi.org/10.3390/bios15050317 - 15 May 2025

Viewed by 311

Abstract

Rolling circle amplification (RCA) at ambient temperature is prone to false positive signals during nucleic acid detection, which makes it challenging to establish an efficient RCA detection method. The false positive signals are primarily caused by binding of non-target nucleic acids to the [...] Read more.

Rolling circle amplification (RCA) at ambient temperature is prone to false positive signals during nucleic acid detection, which makes it challenging to establish an efficient RCA detection method. The false positive signals are primarily caused by binding of non-target nucleic acids to the circular single-stranded template, leading to non-specific amplification. Here, we present an RCA method for miRNA detection at 37 °C using two circular ssDNAs, each of which is formed by ligating the intramolecularly formed nick (without any splint) in a secondary structure. The specific target recognition is realized by utilizing low concentrations (0.1 nM) of circular ssDNA1 (C1). A phosphorothioate modification is present at G*AATTC on C1 to generate a nick for primer extension during the primer self-generated rolling circle amplification (PG-RCA). The fragmented amplification products are used as primers for the following RCA that serves as signal amplification using circular ssDNA2 (C2). Notably, the absence of splints and the low concentration of C1 significantly inhibits non-target binding, thus minimizing false positive signals. A high concentration (10 nM) of C2 is used to carry out linear rolling circle amplification (LRCA), which is highly specific. This strategy demonstrates a good linear response to 0.01–100 pM of miRNA with a detection limit of 7.76 fM (miR-155). Moreover, it can distinguish single-nucleotide mismatch in the target miRNA, enabling the rapid one-pot detection of miRNA at 37 °C. Accordingly, this method performs with high specificity and sensitivity. This approach is suitable for clinical serum sample analysis and offers a strategy for developing specific biosensors and diagnostic tools. Full article

(This article belongs to the Section Biosensors and Healthcare)

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13 pages, 3541 KiB

Open AccessArticle

Ultrasensitive Bead-Based Immunoassay for Real-Time Continuous Sample Flow Analysis

by Yuri M. Shlyapnikov and Elena A. Shlyapnikova

Biosensors 2025, 15(5), 316; https://doi.org/10.3390/bios15050316 - 15 May 2025

Viewed by 348

Abstract

The performance of heterophase immunoassays is often limited by the kinetics of analyte binding. This problem is partially solved by bead-based assays, which are characterized by rapid diffusion in the particle suspension. However, at low analyte concentrations, the binding rate is still low. [...] Read more.

The performance of heterophase immunoassays is often limited by the kinetics of analyte binding. This problem is partially solved by bead-based assays, which are characterized by rapid diffusion in the particle suspension. However, at low analyte concentrations, the binding rate is still low. Here, we demonstrate a further improvement of analyte binding kinetics in bead-based immunoassays by simultaneously concentrating both an analyte and magnetic beads in a compact spatial region where binding occurs. The analyte is electrophoretically concentrated in a flow cell where beads are magnetically retained and dragged along the channel by viscous force. The flow cell is integrated with a microarray-based signal detection module, where beads with bound analyte scan the microarray surface and are retained on it by single specific interactions, assuring ultra-high sensitivity of the method. Thus, a continuous flow assay system is formed. Its performance is demonstrated by simultaneous detection of model pathogen biomarkers, cholera toxin (CT) and staphylococcal enterotoxin B (SEB), with a detection limit of 0.1 fM and response time of under 10 min. The assay is capable of real-time online sample monitoring, as shown by a 12 h long continuous flow analysis of tap water for SEB and CT. Full article

(This article belongs to the Special Issue Design, Fabrication, and Applications of Microfluidic Devices for Biosensing)

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15 pages, 6161 KiB

Open AccessArticle

Chiral-Dependent Redox Capacitive Biosensor Using Cu-Cys-GSH Nanoparticles for Ultrasensitive H₂O₂ Detection

by Duygu Yilmaz Aydin, Jie Jayne Wu and Jiangang Chen

Biosensors 2025, 15(5), 315; https://doi.org/10.3390/bios15050315 - 14 May 2025

Viewed by 284

Abstract

Copper-thiolate nanostructures, formed through the self-assembly of cysteine (Cys) and glutathione (GSH) with copper ions, offer a versatile platform for redox-active applications due to their structural stability and chemical functionality. In this study, Cu-Cys-GSH nanoparticles were synthesized and employed to develop a capacitive [...] Read more.

Copper-thiolate nanostructures, formed through the self-assembly of cysteine (Cys) and glutathione (GSH) with copper ions, offer a versatile platform for redox-active applications due to their structural stability and chemical functionality. In this study, Cu-Cys-GSH nanoparticles were synthesized and employed to develop a capacitive biosensor for the ultralow concentration detection of hydrogen peroxide (H₂O₂). The detection mechanism leverages a Fenton-like reaction, where H₂O₂ interacts with Cu-Cys-GSH nanoparticles to generate hydroxyl radicals (·OH) through redox cycling between Cu²⁺ and Cu⁺ ions. These redox processes induce changes in the sensor’s surface charge and dielectric properties, enabling highly sensitive capacitive sensing at gold interdigitated electrodes (IDEs). The influence of chirality on sensing performance was investigated by synthesizing nanoparticles with both L- and D-cysteine enantiomers. Comparative analysis revealed that the stereochemistry of cysteine impacts the catalytic activity and sensor response, with Cu-L-Cys-GSH nanoparticles exhibiting superior performance. Specifically, the biosensor achieved a linear detection range from 1.0 fM to 1.0 pM and demonstrated an ultra-sensitive detection limit of 21.8 aM, outperforming many existing methods for H₂O₂ detection. The sensor’s practical performance was further validated using milk and saliva samples, yielding high recovery rates and confirming its robustness and accuracy for real-world applications. This study offers a disposable, low-cost sensing platform compatible with sustainable healthcare practices and facilitates easy integration into point-of-care diagnostic systems. Full article

(This article belongs to the Special Issue Innovative Biosensing Technologies for Sustainable Healthcare)

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19 pages, 6179 KiB

Open AccessArticle

Automatic Calculation of Average Power in Electroencephalography Signals for Enhanced Detection of Brain Activity and Behavioral Patterns

by Nuphar Avital, Nataniel Shulkin and Dror Malka

Biosensors 2025, 15(5), 314; https://doi.org/10.3390/bios15050314 - 14 May 2025

Viewed by 490

Abstract

Precise analysis of electroencephalogram (EEG) signals is critical for advancing the understanding of neurological conditions and mapping brain activity. However, accurately visualizing brain regions and behavioral patterns from neural signals remains a significant challenge. The present study proposes a novel methodology for the [...] Read more.

Precise analysis of electroencephalogram (EEG) signals is critical for advancing the understanding of neurological conditions and mapping brain activity. However, accurately visualizing brain regions and behavioral patterns from neural signals remains a significant challenge. The present study proposes a novel methodology for the automated calculation of the average power of EEG signals, with a particular focus on the beta frequency band which is known for its pronounced activity during cognitive tasks such as 2D content engagement. An optimization algorithm is employed to determine the most appropriate digital filter type and order for EEG signal processing, thereby enhancing both signal clarity and interpretability. To validate the proposed methodology, an experiment was conducted with 22 students, during which EEG data were recorded while participants engaged in cognitive tasks. The collected data were processed using MATLAB (version R2023a) and the EEGLAB toolbox (version 2022.1) to evaluate various filters, including finite impulse response (FIR) and infinite impulse response (IIR) Butterworth and IIR Chebyshev filters with a 0.5% passband ripple. Results indicate that the IIR Chebyshev filter, configured with a 0.5% passband ripple and a fourth-order design, outperformed the alternatives by effectively reducing average power while preserving signal fidelity. This optimized filtering approach significantly improves the accuracy of neural signal visualizations, thereby facilitating the creation of detailed brain activity maps. By refining the analysis of EEG signals, the proposed method enhances the detection of specific neural behaviors and deepens the understanding of functional brain regions. Moreover, it bolsters the reliability of real-time brain activity monitoring, potentially advancing neurological diagnostics and insights into cognitive processes. These findings suggest that the technique holds considerable promise for future applications in brain–computer interfaces and advanced neurological assessments, offering a valuable tool for both clinical practice and research exploration. Full article

(This article belongs to the Section Biosensor and Bioelectronic Devices)

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14 pages, 4266 KiB

Open AccessArticle

One-Step Labeling Based on Eu-MOFs to Develop Fluorescence Side-Flow Immunoassay for AFB1 Detection in Corn

by Yinjun Li, Hua Ding, Ziyu Wang, Zewei Luo and Xitian Peng

Biosensors 2025, 15(5), 313; https://doi.org/10.3390/bios15050313 - 14 May 2025

Viewed by 286

Abstract

Lateral flow immunoassay (LFIA) is a promising tool for rapid detection in the field of agricultural product analysis due to its advantages of cost-effectiveness and operational simplicity. In this work, Eu metal–organic frameworks (MOFs) were introduced to LFIA as a rapid detection method [...] Read more.

Lateral flow immunoassay (LFIA) is a promising tool for rapid detection in the field of agricultural product analysis due to its advantages of cost-effectiveness and operational simplicity. In this work, Eu metal–organic frameworks (MOFs) were introduced to LFIA as a rapid detection method characterized by high stability and low interference. Key research objectives included strong fluorescence, ease of labeling, and the utilization of fluorescent probes. Eu-MOFs were synthesized in one step via the hydrothermal method, exhibiting a fluorescence lifetime of 163 μs and spherical particles with diameters ranging from 250 to 400 nm. These conditions fulfill the characteristics and requirements of LFIA. Eu-MOFs exploit the porous nature of MOFs to mitigate the drawbacks associated with complex crosslinking agents. This enables antibody proteins to be cross-linked merely upon contact, thereby simplifying the detection process. A time-resolved LFIA method was developed utilizing Eu-MOFs for the detection of aflatoxin B1 (AFB1) in corn, achieving a limit of detection (LOD, IC10) of 0.149 ng/mL. The accuracy and reliability of the Eu-MOFs-LFIA method were validated through comparisons with spiked concentrations during spiking and blind sample analyses, with verification conducted using ultra-high-performance liquid chromatography mass spectrometry (UPLC-MS). Furthermore, testing of real samples demonstrated that the Eu-MOFs-LFIA method can effectively facilitate rapid detection of AFB1 in corn. Full article

(This article belongs to the Special Issue Optical Fiber Biochemical and Environmental Sensors)

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22 pages, 3776 KiB

Open AccessReview

Challenges in Adapting Fibre Optic Sensors for Biomedical Applications

by Sahar Karimian, Muhammad Mahmood Ali, Marion McAfee, Waqas Saleem, Dineshbabu Duraibabu, Sanober Farheen Memon and Elfed Lewis

Biosensors 2025, 15(5), 312; https://doi.org/10.3390/bios15050312 - 13 May 2025

Viewed by 589

Abstract

Fibre optic sensors (FOSs) have developed as a transformative technology in healthcare, often offering unparalleled accuracy and sensitivity in monitoring various physiological and biochemical parameters. Their applications range from tracking vital signs to guiding minimally invasive surgeries, enabling advancements in medical diagnostics and [...] Read more.

Fibre optic sensors (FOSs) have developed as a transformative technology in healthcare, often offering unparalleled accuracy and sensitivity in monitoring various physiological and biochemical parameters. Their applications range from tracking vital signs to guiding minimally invasive surgeries, enabling advancements in medical diagnostics and treatment. However, the integration of FOSs into biomedical applications faces numerous challenges. This article describes some challenges for adopting FOSs for biomedical purposes, exploring technical and practical obstacles, and examining innovative solutions. Significant challenges include biocompatibility, miniaturization, addressing signal processing complexities, and meeting regulatory standards. By outlining solutions to the stated challenges, it is intended that this article provides a better understanding of FOS technologies in biomedical settings and their implementation. A broader appreciation of the technology, offered in this article, enhances patient care and improved medical outcomes. Full article

(This article belongs to the Special Issue Feature Papers of Biosensors)

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10 pages, 1735 KiB

Open AccessCommunication

Wearable Humidity Sensor Using Cs₃Cu₂I₅ Metal Halides with Hydroxyl Selective Phase Transition for Breath Monitoring

by Si Hyeok Yang, Lim Kyung Oh, Dong Ho Lee, Donghoon Gwak, Nara Song, Bowon Oh, Na Young Lee, Hongki Kim, Han Seul Kim and Jin Woo Choi

Biosensors 2025, 15(5), 311; https://doi.org/10.3390/bios15050311 - 13 May 2025

Viewed by 387

Abstract

The low-dimensional metal halide Cs₃Cu₂I₅ exhibits unique electrical and chemical properties. Notably, it undergoes a phase transition to CsCu₂I₃ upon exposure to hydroxyl (-OH) gas, resulting in significant changes in its electrical characteristics. In this [...] Read more.

The low-dimensional metal halide Cs₃Cu₂I₅ exhibits unique electrical and chemical properties. Notably, it undergoes a phase transition to CsCu₂I₃ upon exposure to hydroxyl (-OH) gas, resulting in significant changes in its electrical characteristics. In this study, we developed a highly selective semiconductor-based gas sensor utilizing Cs₃Cu₂I₅. The material was synthesized on an Al₂O₃ substrate with carbon electrodes using a solution-based process, enabling gas sensing based on its electrical properties. The sensor was further integrated into an Arduino-based real-time monitoring system for wearable applications. The final system was mounted onto a face mask, enabling the real-time detection of human respiration. This research presents a next-generation sensor platform for real-time respiratory monitoring, demonstrating the potential of Cs₃Cu₂I₅ in advanced wearable bio-gas sensing applications. Full article

(This article belongs to the Special Issue Wearable Biosensors and Health Monitoring)

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13 pages, 2896 KiB

Open AccessArticle

Individually Modified Microneedle Array for Minimal Invasive Multi-Electrolyte Monitoring

by Ketian Yu, Yukun Ma, Yiming Wei, Wanying Chen, Zhen Dai, Yu Cai, Xuesong Ye and Bo Liang

Biosensors 2025, 15(5), 310; https://doi.org/10.3390/bios15050310 - 12 May 2025

Viewed by 328

Abstract

Electrolytes play crucial roles in regulating nerve and muscle functions. Currently, microneedle technology enables real-time electrolyte monitoring through minimally invasive methods. However, due to the small size of microneedles, performing multi-layer modifications on individual microneedles and ensuring the integrity of these layers pose [...] Read more.

Electrolytes play crucial roles in regulating nerve and muscle functions. Currently, microneedle technology enables real-time electrolyte monitoring through minimally invasive methods. However, due to the small size of microneedles, performing multi-layer modifications on individual microneedles and ensuring the integrity of these layers pose significant challenges. Additionally, the puncture efficiency of the electrodes will be affected by the structure of microneedle array integration. To address these issues, we primarily focus on developing a multi-parameter ion monitoring system based on microneedle arrays. By optimizing the surface reconstruction of electrode substrates, the adhesion between the electrode surface and the modification layer was improved, enhancing the stability of the electrodes. Potassium, sodium, and calcium ion-selective electrodes based on microneedles were fabricated, demonstrating good sensitivity and linearity. To tackle the puncture efficiency of microneedle arrays, finite element simulation was employed to investigate the mechanical properties of different structural designs of microneedle arrays during skin insertion. Ultimately, an integrated microneedle array was designed and assembled, and a multi-parameter ion monitoring system was developed, validated through in vitro simulations and in vivo animal experiments. This research provides valuable insights into the development and advancement of minimally invasive, multi-parameter dynamic monitoring technologies in clinical settings. Full article

(This article belongs to the Section Nano- and Micro-Technologies in Biosensors)

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45 pages, 15184 KiB

Open AccessReview

Wearable Electrochemical Glucose Sensors for Fluid Monitoring: Advances and Challenges in Non-Invasive and Minimally Invasive Technologies

by Ming Wang, Junjie Zheng, Ge Zhang, Shiyan Lu and Jinli Zhou

Biosensors 2025, 15(5), 309; https://doi.org/10.3390/bios15050309 - 12 May 2025

Viewed by 1017

Abstract

This review highlights the latest developments in wearable electrochemical glucose sensors, focusing on their transition from invasive to non-invasive and minimally invasive designs. We discuss the underlying mechanisms, performance metrics, and practical challenges of these technologies, emphasizing their potential to revolutionize diabetes care. [...] Read more.

This review highlights the latest developments in wearable electrochemical glucose sensors, focusing on their transition from invasive to non-invasive and minimally invasive designs. We discuss the underlying mechanisms, performance metrics, and practical challenges of these technologies, emphasizing their potential to revolutionize diabetes care. Additionally, we explore the motivation behind this review: to provide a comprehensive analysis of emerging sensing platforms, assess their clinical applicability, and identify key research gaps that need addressing to achieve reliable, long-term glucose monitoring. By evaluating electrochemical sensors based on tears, saliva, sweat, urine, and interstitial fluid, this work aims to guide future innovations toward more accessible, accurate, and user-friendly solutions for diabetic patients, ultimately improving their quality of life and disease management outcomes. Full article

(This article belongs to the Special Issue Wearable and Implantable Bioelectronics for Advanced Biosensing and Human Health Monitoring)

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14 pages, 6839 KiB

Open AccessArticle

Analysis of Colorectal Cancer Gene Mutations and Application of Long Blocker Displacement Amplification Technology for High-Throughput Mutation Detection

by Ping Lu, Xinglei Su, Sirui Leong, Xuehao Xiu, Ping Song, Junjie Peng and Yunpei Si

Biosensors 2025, 15(5), 308; https://doi.org/10.3390/bios15050308 - 12 May 2025

Viewed by 369

Abstract

Genetic mutation detection for colorectal cancer (CRC) is crucial for precision diagnosis and treatment, yet current methods often suffer from challenges such as low sensitivity, time consumption, and high costs. In our preliminary bioinformatic analysis of 751 CRC cases from The Cancer Genome [...] Read more.

Genetic mutation detection for colorectal cancer (CRC) is crucial for precision diagnosis and treatment, yet current methods often suffer from challenges such as low sensitivity, time consumption, and high costs. In our preliminary bioinformatic analysis of 751 CRC cases from The Cancer Genome Atlas and 131 Chinese patient samples, APC, TP53, and KRAS were identified as the most frequently mutated genes. Among them, KRAS missense mutations emerged as key diagnostic biomarkers. In this study, we applied a fluorescence-based long block displacement amplification (LBDA) sensing method for the rapid, high-throughput, and cost-effective detection of KRAS genetic mutations. In the LBDA system, SYBR Green dye binds to the amplified double-stranded DNA, generating a fluorescence signal that directly reflects the abundance of mutant types (MTs). This real-time signal output enables the enrichment and sensitive detection of MTs, establishing LBDA as an efficient biosensing platform for KRAS genotyping. Using this technique, a detection limit of 0.08% variant allele frequency was achieved with 20 ng of synthetic DNA input. To evaluate clinical performance, the LBDA method was applied to 118 tissue samples from 59 CRC patients, including tumor and matched peritumoral tissues. For 59 CRC tumor samples, LBDA successfully identified KRAS mutations in 37.29% of cases, closely matching results (42.37%) obtained by next-generation sequencing and achieving 88% sensitivity and 100% specificity. In conclusion, this study presents a rapid and cost-effective mutation detection method based on optical biosensing, offering strong potential for advancing personalized CRC diagnosis and treatment. Full article

(This article belongs to the Special Issue DNA Molecular Engineering-Based Biosensors)

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14 pages, 2078 KiB

Open AccessArticle

A Microfluidic Device Integrating a Glucose Sensor and Calibration Function for Cell-Based Assays

by Laner Chen, Kenta Shinha, Hiroko Nakamura, Kikuo Komori and Hiroshi Kimura

Biosensors 2025, 15(5), 307; https://doi.org/10.3390/bios15050307 - 11 May 2025

Viewed by 453

Abstract

Microphysiological systems (MPS) incorporating microfluidic technologies offer improved physiological relevance and real-time analysis for cell-based assays, but often lack non-invasive monitoring capabilities. Addressing this gap, we developed a microfluidic cell-based assay platform integrating an electrochemical biosensor for real-time, non-invasive monitoring of kinetic cell [...] Read more.

Microphysiological systems (MPS) incorporating microfluidic technologies offer improved physiological relevance and real-time analysis for cell-based assays, but often lack non-invasive monitoring capabilities. Addressing this gap, we developed a microfluidic cell-based assay platform integrating an electrochemical biosensor for real-time, non-invasive monitoring of kinetic cell status through glucose consumption. The platform addresses the critical limitations of traditional cell assays, which typically rely on invasive, discontinuous methods. By combining enzyme-modified platinum electrodes within a microfluidic device, our biosensor can quantify dynamic changes in glucose concentration resulting from cellular metabolism. We have integrated a calibration function that corrects sensor drift, ensuring accurate and prolonged short-term measurement stability. In the validation experiments, the system successfully monitored glucose levels continuously for 20 h, demonstrating robust sensor performance and reliable glucose concentration predictions. Furthermore, in the cell toxicity assays using HepG2 cells exposed to varying concentrations of paraquat, the platform detected changes in glucose consumption, effectively quantifying the cellular toxicity responses. This capability highlights the device’s potential for accurately assessing the dynamic physiological conditions of the cells. Overall, our integrated platform significantly enhances cell-based assays by enabling continuous, quantitative, and non-destructive analysis, positioning it as a valuable tool for future drug development and biomedical research. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications (3rd Edition))

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19 pages, 6630 KiB

Open AccessArticle

Improving the Accuracy of a Wearable Uroflowmeter for Incontinence Monitoring Under Dynamic Conditions: Leveraging Machine Learning Methods

by Faezeh Shanehsazzadeh, John O. L. DeLancey and James A. Ashton-Miller

Biosensors 2025, 15(5), 306; https://doi.org/10.3390/bios15050306 - 11 May 2025

Viewed by 395

Abstract

Urinary incontinence affects many women, yet there are no monitoring devices capable of accurately capturing flow dynamics during everyday activities. Building on our initial development of a wearable personal uroflowmeter, this study enhances the device’s performance under realistic, dynamic conditions similar to those [...] Read more.

Urinary incontinence affects many women, yet there are no monitoring devices capable of accurately capturing flow dynamics during everyday activities. Building on our initial development of a wearable personal uroflowmeter, this study enhances the device’s performance under realistic, dynamic conditions similar to those encountered in daily living. We integrated an optimized eight-vane Etoile flow conditioner with a 0.2D opening into the device. Both computational fluid dynamics simulations and experimental tests demonstrated that this flow conditioner significantly reduced turbulence intensity by 82% and stabilized the axial velocity profile by 67%, increasing the R² of flow rate measurements from 0.44 to 0.92. Furthermore, our machine learning framework—utilizing a support vector machine (SVM) and an extreme gradient boosting (XGBoost) model with principal component analysis (PCA)—accurately predicted the true flow rate with high correlations, robust performance, and minimal overfitting. For the test dataset, the SVM achieved a correlation of 0.86, an R² of 0.74, and an MAE of 2.8, whereas the XGBoost-PCA model exhibited slightly stronger performance, with a correlation of 0.88, an R² of 0.76, and an MAE of 2.6. These advances established a solid foundation for developing a reliable, wearable uroflowmeter capable of effectively monitoring urinary incontinence in real-world settings. Full article

(This article belongs to the Special Issue Advances in Flexible and Wearable Biosensors)

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21 pages, 5217 KiB

Open AccessArticle

Gait Phase Recognition in Multi-Task Scenarios Based on sEMG Signals

by Xin Shi, Xiaheng Zhang, Pengjie Qin, Liangwen Huang, Yaqin Zhu and Zixiang Yang

Biosensors 2025, 15(5), 305; https://doi.org/10.3390/bios15050305 - 10 May 2025

Viewed by 302

Abstract

In the human–exoskeleton interaction process, accurately recognizing gait phases is crucial for effectively assessing the assistance provided by the exoskeleton. However, due to the similarity in muscle activation patterns between adjacent gait phases, the recognition accuracy is often low, which can easily lead [...] Read more.

In the human–exoskeleton interaction process, accurately recognizing gait phases is crucial for effectively assessing the assistance provided by the exoskeleton. However, due to the similarity in muscle activation patterns between adjacent gait phases, the recognition accuracy is often low, which can easily lead to confusion in surface electromyography (sEMG) feature extraction. This paper proposes a real-time recognition method based on multi-scale fuzzy approximate root mean entropy (MFAREn) and an Efficient Multi-Scale Attention Convolutional Neural Network (EMACNN), building upon the concept of fuzzy approximate entropy. MFAREn is used to extract the dynamic complexity and energy intensity features of sEMG signals, serving as the input matrix for EMACNN to achieve fast and accurate gait phase recognition. This study collected sEMG signals from 10 subjects performing continuous lower limb gait movements in five common motion scenarios for experimental validation. The results show that the proposed method achieves an average recognition accuracy of 95.72%, outperforming the other comparison methods. The method proposed in this paper is significantly different compared to other methods (p < 0.001). Notably, the recognition accuracy for walking in level walking, stairs ascending, and ramp ascending exceeds 95.5%. This method demonstrates a high recognition accuracy, enabling sEMG-based gait phase recognition and meeting the requirements for effective human–exoskeleton interaction. Full article

(This article belongs to the Section Wearable Biosensors)

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16 pages, 1919 KiB

Open AccessArticle

Multi-Parametric Electrochemical Sensing Platform: Applications in Animal Welfare

by C. Ferreira, E. Lynch, A. O’Herlihy, F. Barry, L. C. Nagle, S. R. Teixeira and P. Galvin

Biosensors 2025, 15(5), 304; https://doi.org/10.3390/bios15050304 - 10 May 2025

Viewed by 389

Abstract

The rapid growth of the dairy sector requires advanced monitoring tools to ensure sustainable practices that benefit the environment, economy, and human health. Current monitoring devices often lack multi-parametric capabilities, limiting their ability to provide comprehensive data on critical chemical and biochemical parameters. [...] Read more.

The rapid growth of the dairy sector requires advanced monitoring tools to ensure sustainable practices that benefit the environment, economy, and human health. Current monitoring devices often lack multi-parametric capabilities, limiting their ability to provide comprehensive data on critical chemical and biochemical parameters. To address this challenge, this work presented the integration of a real-time multi-parametric device with sensors for pH, temperature, nitrate, and nitrite, providing a comprehensive solution to dairy cattle health monitoring. This solution included an electrochemical platform, Portable Unit for Lab-on-Site Electrochemistry (PULSE), and an application for data processing and display. In-house fabricated flexible gold-printed electrodes demonstrated accurate detection of nitrite and nitrate when integrated with the PULSE, achieving sensitivities of 6.32

μ

A/ppm/

{cm}^{2}

in artificial interstitial fluid and 1.92

μ

A/ppm/

{cm}^{2}

in phosphate buffered saline, respectively. The PULSE achieved 65.83% and 58.3% lower limits of detection in phosphate buffered saline than a benchtop potentiostat, for nitrate and nitrite, respectively, along with a 24.5% increase in nitrite sensitivity, enhancing its ability to detect lower analyte concentrations. pH sensing was carried out with a commercial screen-printed electrode coated with a layer of iridium oxide. The pH was tested in ruminal complex fluid, obtaining a pH sensitivity of −59.63 mV/pH and an accuracy of 98.9%. These findings highlighted the potential of this technology as an effective tool for dairy cattle health monitoring and its deployment in real-world scenarios. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanotechnology: From Fabrication Methods and Improvement Strategies to Applications in Biosensing and Biomedicine (2nd Edition))

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